Signal scrambling and descrambling has been effected heretofore in a number of different ways with a view to restricting intelligible reception to those for whom such reception is intended. Thus, for example, audio information has been scrambled prior to its being used for modulating a carrier wave for wireless or cable transmission and has been descrambled at authorized receivers after the received modulated carrier wave has been demodulated. Another known secure transmission technique has involved a 180.degree. phase inversion of either sideband or carrier components of a modulated signal with subsequent reinversion at a receiver. In cable television systems, it has moreover been known to transmit video sidebands while partially or completely suppressing the carrier, such transmission being accompanied by the transmission of a pilot signal having a frequency of some precise submultiple, e.g. one-half, of the carrier frequency and in phase with the carrier. Then, prior to carrying out the demodulation process in the receiver, the pilot signal is multiplied by the factor necessary to reestablish the carrier frequency and phase. This technique, however, is not employable for those wireless transmissions which must be within assigned frequency bands coinciding with the bands for which the receiver is designed, nor for cable systems not having unused or available spectra to accommodate such pilot signals. And, the 180.degree. phase inversion technique has somewhat less than the security required for video signal transmission in pay television systems, as the sync circuits of unauthorized receivers can fortuitiously lock on to such a transmission and result, at least occasionally at random, in the production of an intelligible picture.